Recording medium for a spark burning recorder

ABSTRACT

A recording medium for a spark burning recorder having a base sheet, a colored layer formed on the base sheet and an aluminum layer formed on the colored layer by vapor deposition. The glossiness of the aluminum layer is less than 20 percent.

United States Patent [191 Tokumoto et al.

[451 Jan. 21, 1975 RECORDING MEDIUM FOR A SPARK BURNING RECORDER [75] Inventors: Shinichi Tokumoto, Yokohama;

Chisayo Hayashi, Fujisawa, both of Japan [73] Assignee: Sony Corporation, Tokyo, Japan [22] Filed: Jan. 31, 1972 [21] Appl. No.: 222,007

[30] Foreign Application Priority Data Jan. 30, 1971 Japan 46-3507 Jan. 30, 1971 Japan 46-3508 [52] US. Cl 117/217, 117/107, 117/218,

117/227, 346/74 S, 346/74 SB, 346/74 SC, 346/135 [51] Int. Cl. B44d 1/16, B44d1/18, GOld 15/08 [58] Field of Search 117/107, 217, 218, 62,

117/213, 227', 346/74 S, 74 SB, 74 SC, 135

[56] References Cited UNITED STATES PATENTS 2,833,677 5/1958 Baumlein 346/135 3,377,599 4/1968 Reis 117/217 3,434,878 3/1969 Rcis 117/217 3,689,768 9/1972 Sato et a1 346/135 3,758,336 9/1973 Reichlc 117/107 Primary ExaminerCameron K. Wciffcnbach Attorney, Agent, or Firm-Lcwis H. Eslingcr; Alvin Sinderbrand [57] ABSTRACT A recording medium for a spark burning recorder having a base sheet, a colored layer formed on the base sheet and an aluminum layer formed on the colored layer by vapor deposition. The glossiness of the aluminum layer is less than 20 percent.

12 Claims, 13 Drawing Figures PATENTED 3,861,952

SHEET 10F 3 FIG. 1

. PRIOR ART RECORDING MEDIUM FOR A SPARK BURNING RECORDER BACKGROUND OF THE INVENTION This invention relates to a recording medium for a spark burning recorder and more particularly to a metallized recording paper on which the recorded image can be easily seen.

A spark burning recorder is well known in which image is recorded on a metallized recording paper by sparking, as shown, for instance, in US. Pat. No. 3,074,066. A recorder of this type has an advantage in that it can be printed on at a higher rate and without noise. Moreover no troublesome operations such as developing treatments are required, when it is used. Such recorders are used not only to record a letter, a figure, a mark and the like, but also to record a picture of facsimile.

A metallized paper used for such a recorder is formed by coating a white paper with a metallic layer such as aluminum. The glossiness on the surface of the paper has the disadvantage that the recorded pattern can be seen by transmitting light from the back side, but it can scarcely be seen by reflected light. Furthermore, a recording paper in which a graphite layer and a coating layer containing zinc oxide are formed on a white paper has the further disadvantage that dust and bad smell occur when an image is recorded on it.

In order to obviate these disadvantages, a recording medium has been proposed in which a black conductive layer containing graphite powder is formed on a white paper, and an aluminum layer is formed on the black conductive layer by vapor deposition. This recording paper has the advantage that dust and bad smell scarcely occur and a recorded pattern can be easily seen because of the black conductive layer. However, it has the fatal disadvantage that the surface of the aluminum layer becomes corroded while in storage for a long time, and so it is difficult to store the record as it is. It has another disadvantage in that the glossiness of the aluminum layer is great and so it is difficult to see the recorded pattern on it at certain positions of a light source.

OBJECTS OF THE INVENTION It is thus a primary object of this invention to provide a recording medium of reduced glossiness which does not have the disadvantages of media now available.

It is a further object of this invention to provide a recording medium which does not have the visual and dust disadvantages encountered with the medium discussed above and which can be stored for extended periods.

SUMMARY OF THE INVENTION These and other objects of this invention are achieved with a recording medium according to the invention. A metal layer with a rough surface is formed on a paper having a colored layer, thereby creating an irregularly reflecting surface on the paper wherein the glossiness is lowered below 20 percent, and preferably below l5 percent. A non-conductive layer is formed in contact with the under surface of the metal layer, so that the pattern recorded on it can be seen by the naked eye and so that it is possible to store the record on it for a long time.

The glossiness of the surface is measured by Methods of Measurement for Glossiness, JIS Z 8741-1962, Japanese Industrial Standard (JIS) investigated by Japanese Industiral Standards Committee. The measuring method is described below in detail.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a schematic side elevation showing a spark burning recorder with which a recording medium according to this invention can be used;

FIGS. 2-11, except FIG. 7, are enlarged sectional views showing the preferred embodiments of the recording medium according to this invention; and

FIG. 7 is an enlarged sectional view of a comparative example of a recording medium used for description of this invention.

DETAILED DESCRIPTION FIG. I shows the fundamental principle of the conventional spark burning recorder. In the FIG. I, numeral 1 is a recording medium in which a conductive thin film, for instance, a vapor-deposited aluminum layer 3 is formed on a white paper 2. The recording medium l is placed between a conductive roll 4 and a platen 5 to be moved by means of a motor M. A stylus 6 contacts the vapor-deposited aluminum thin film or layer 3 on the recording medium I on the platen 5. The stylus 6 is attached to an apparatus (not shown) for scanning in the direction substantially perpendicular to the direction in which the recording medium advances. When a signal voltage, for instance, a DC or pulse voltage is supplied to input terminals 7 and 8, the voltage near the stylus 6 drops, and the Joules heat concen' trates at that spot, causing a part of the vapor-deposited aluminum layer 3 to be removed. Consequently, holes of sizes proportional to supplied voltages are formed on the aluminum layer 3, and a desired pattern or mark is recorded on it.

The conventional recording paper has the abovementioned disadvantages that the glossiness of the aluminum layer is not only great, but also that it is difficult to store the record for a long period. According to experiments performed by the inventors herein, the recording paper in which the aluminum film is vapordeposited on paper smoothed by a resin-coating of its surface, has a glossiness of 76 percent and a density of I68. It has been recognized that the aluminum film on the paper contrasts weakly with the color of the paper, and so the paper is not suitable for recording. A glossiness of 20 percent can be obtained by roughing the surface to be vapor-deposited by aluminum. In this way a density of 0.3 was obtained. The experiments showed that this value is an upper limit for practically satisfactory glossiness. Glossiness of less than 20 percent is desirable and it is preferred that the glossiness and the density of the paper be below 15 percent and 0.16, respectively.

Experiments on the corrosion of the aluminum layer in storage, using different materials for the colored layer such as pigment, dye and the like, showed that corrosion does not occur when the aluminum layer contacts only a layer containing no conductive material such as conductive pigment, and that the cause of the corrosion is the formation of local cells due to extrance of water vapor in the atmosphere between the aluminum layer and the conductive pigment.

Recording mediums formed according to the invention are described in the following examples. As the thickness of the aluminum layer in the examples cannot be measured exactly because of its roughness, the aluminum layer is vapor-deposited so that its surface resistance is 1.8 to 2.2 ohm/cm? It is difficult to define the thickness of the aluminum layer, because it varies in accordance with the voltage and current used in the recording. Practically, it is desirable to control the surface resistance in the range of 0.5 to 5 ohm/cm? The glossiness is measured by Method 1" defined in JIS Z 8741-1962. In this method, a parallel light making an angle of 75 with a surface perpendicular to the surface of the sample is converted to a voltage by a photovoltaic cell disposed on a line making an angle of 75 with the perpendicular surface. The glossiness is represented by a ratio of a voltage of an output from the photovoltaic cell on the sample to a voltage of an output from the photovoltaic cell on a glass of refractive index 1.567 instead of the sample, as the glossiness of the latter voltage is 100 percent.

The density or reflection density of the recorded pattern is measured by a Yamabe densitometer. This measurement is performed by the naked-eye. A comparison of the density of baryta paper for a photograph is zero and lights from two light-sources are applied to the sample and the standard paper at an angle of 45, respectively.

EXAMPLE 1 As shown in FIG. 2, a polyethylene film 12 was laminated on a black vellum paper 11. The surface of the film was roughened by sandblasting using abrasive material with a grain size of mean diameter 0.34 mm. An aluminum layer 13 was formed on a base consisting of the polyethylene film 12 and the black vellum paper 11 by vapor deposition of aluminum. Thus, a recording medium 14 of glossiness 15 percent and surface resistance 0.5 ohm/cm was obtained. Its density was 0.13 and the density of the vellum paper in the holes or recorded pattern was 1.70 after recording by the recorder shown in FIG. 1. A recorded pattern with high contrast of density difference 1.57 was obtained.

EXAMPLE 2 Cellulose acetate dissolved in acetone was coated on brown glassine, and dried in an atmosphere of 70 percent humidity. A mat with a thickness of 0.5 to 1 micron was formed on the surface of the cellulose acetate layer due to the humidity. A recording medium with a grey surface was obtained by aluminum vapor deposition on the surface. The recording medium had a surface resistance of 1.2 ohmlcm a glossiness of 13 percent and a density of 0.13.

EXAMPLE 3 The composition given below was fully mixed by a ball-mill and was then coated on a white paper of fine quality by a roll-coater. It was then dried and aluminum was vapor-deposited on the composition.

Binding agent (Vinyl chloride-acetate copolymer,

for example, Vinylite VYHH trademark) 10 g -Continued Spirit Black (Oil soluble dye) 2 Magnesium Carbonate (Pigment for adjusting roughness) 2 g Magnesium Oxide (Pigment for adjusting roughness) l g Solvent (Mixture of cyclohexanone and acetone) 65 g FIG. 3 shows the structure of the recording medium which is comprised of a sheet 31 of white paper of fine quality, non-conductive pigment layer 32 colored with dye and formed on the sheet 31, and vapor-deposited aluminum layer 33 formed on the pigment layer 32.

The surface of the vapor-deposited aluminum layer 33 obtained in this example had a glossiness of 13.5 percent and a density of 0.15. When the recording medium was removed by pulse signals of 300 u sec and a DC voltage of 30 V at a recording rate of 60 cm/sec,

using the equipment shown in FIG. 1, the density of the v exposed base layer was 1.70. Thus, a black clean recorded pattern was obtained in a high contrast of 1.55 in density difference. The surface resistance of the recording medium was 1.2 ohm/cm? No vanishing, no contamination and no damage to the recorded pattern occurred in the recording medium due to electrolyticcorrosion of the aluminum layer, after the recording medium was subjected to an atmosphere of percent relative humidity at normal temperature for a week.

As mentioned above, the layer containing nonconductive pigment adjusts the roughness of the vapordeposited aluminum layer and a dye is used for the coloring material in the layer. The glossiness of the vapordeposited aluminum layer can thus be lowered without using any special means. Moreover, as the layer is capable of adjusting the roughness and the coloring is nonconductive, a recording medium of good quality is obtained without incurring electrolytic-corrosion between the aluminum and the layer.

EXAMPLE 4 As shown in FIG. 4, the first layer 42 consists of nonconductive pigment formed on a sheet 41 of fine quality white paper and was of the same composition shown in Example 3. The second layer, 43, of non-conductive pigment consists of alkyd resin coating containing barium sulfate of a smaller grain size than the grain size in the first layer of non-conductive pigment 42. The second layer was coated on the first layer 42 in a thickness of l to 2 p. and then the vapor-deposited aluminum layer 44 was formed on the second layer 43.

A recording medium of glossiness 7.2 percent and density 0.10 was obtained. No corrosion occurred in the recording medium after it was subjected to an atmosphere of 95 percent relative humidity at normal temperature for a week.

In this example, as the first layer 42 of nonconductive pigment was capable of adjusting the roughness of the surface and of coloring, and the second layer 43 of non-conductive pigment was capable of adjusting the roughness of the surface more finely than the first layer 42 of non-conductive pigment, a surface of satisfactory qualitites was obtained, suitable for the recording of a picture such as a facsimile.

EXAMPLE 5 The composition given below was fully mixed by a ball-mill and was coated on a fine quality white paper by a roll-coater. It was then dried and aluminum was vapor-deposited on the layer of composition. A recording medium of glossiness 14 percent and density 0.15 was obtained. The medium was hardly eorrodable.

Cellulose acetatebutyrate g Oil Blue G 0.1 g

Magnesium Carbonate 2 g Magnesium Oxide l g Solvent (Mixture of cyclohexanone and acetone) 65 g EXAMPLE 6 Cellulose acetatebutyrate l0 Magnesium Carbonate 2 Magnesium Oxide l Solvent (Mixture of eyclohexanone and acetone) 65 the dye. Non-conductive, organic pigments such as lake which have both the function of a dye and the function of adjusting the roughness may also be used.

The metal for the vapor-deposited layer is not limited to aluminum, but may also be a corrosion resistant aluminum alloy containing, for example, 2 to 3 percent magnesium or impurities, as for example, copper, silicon, iron, manganese, zinc, chromium in less than about 0.3 percent respectively with respect to aluminum.

An oil coating on the vapor-deposited layer of the recording medium improves the spark burning effect and prevents mechanical damage due to scanning of the stylus of a recording.

FIG. 7 sets forth a comparative example of a recording medium. As shown in FIG. 7, alkyd resin containing carbon black with a grain size of0.02 to 0.6 ,u is coated on white vellum paper 71 on which a colored layer 72 of conductive pigment was formed. An aluminum layer 73 was formed on layer 72. Thus a recording medium of surface glossiness of 9 percent and density of 0.12 was obtained.

When an image was recorded on this recording medium by the equipment shown in FIG. 1, an image of sufficient contrast was obtained.

The colored layer may be formed by using lead oxide, iron oxide or the like instead of carbon black to obtain an image of high contrast.

A partial disappearance of the aluminum layer occurs in long-term storage of the recording paper. In order to determine the cause, a vapor-deposited aluminum layer formed on each conductive pigment was investigated for its corrosiveness by varying the content of acetylene black by weight to a bonding agent.

The results were as follows:

Acetylene black (Manuf. by Electrical Chemical Industry Co., Ltd.) by weight Resistance of the coated surface at normal temperature 36 hours 15 hours Time of occurrence of corrosion after being subjected to an atmosphere of 90% relative humidity at normal temperature EXAMPLE 7 As shown in FIG. 6, a colored layer 62 of nonconductive black dye was formed on a sheet 61 of white paper of fine quality; a layer 63 of nonconduetive pigment with the same composition described in example 6 was formed on the colored layer 62; and then a vapor-deposited aluminum layer 64 was formed on the layer 63 Thus, a recording medium of the same glossiness and density as in the Example 6 was obtained, which was hardly eorrodable.

Non-conductive, inorganic pigments such as calcium carbonate, barium sulfate, alumina, aluminum trihydrate, magnesium carbonate, magnesia, titanium oxide and the like, and glass-powder may be used as materials for adjusting roughness. Other oil soluble colors, dye for coloring synthetic resin and the like may be used as 48 hours l0 hours [0 hours As seen in the above results, the disappearance of the aluminum layer occurred, even when the amount of acetylene black was minor and the surface resistance was high, i.e., in the order of 10 ohm/cm The experiments show that the cause of the disappearance is the humidity in the atmosphere. The aluminum layer is disintegrated due to the formation of local cells caused by entrance of water between the aluminum layer having a thickness of 0.001 to 0.5 p. and the colored layer of conductive pigment.

The experiments show that this disadvantage is removed by forming an electrical insulating layer comprised of water-proof synthetic resin film which contains no conductive material, between the colored layer and the aluminum layer, when the colored layer is formed by such a conductive or semi-conductive pigment.

EXAMPLE 8 When an insulating layer 83 of vinylidene chloride with a thickness of about 1 p. was formed by dipping, between a colored layer 82 and an aluminum layer 84, using the same material as the recording material in the comparative example shown in FIG. 8, a recording paper of nearly the same glossiness and density so that in the comparative example was obtained. No disappearance of the aluminum layer occurred, after the recording paper was subjected to an atmosphere of 90 percent relative humidity for 48 hours.

In all of the following examples, conductive pigment is used for a colored layer and recording mediums without the above-mentioned disadvantages are shown.

EXAMPLE 9 A colored layer of conductive pigment of carbon black was formed on a white paper; a semi-transparent layer of a mixture of polyester resin and magnesium carbonate was formed on the colored layer with a thickness at which the black colored under layer wasnt optically covered; and aluminum was vapor-deposited on the semi-transparent layer to form a recording medium.

The glossiness of the aluminum surface was reduced to 8 percent because of the semi-transparent layer, and the density was 0.13. The density of the exposed part of the base layer removed by an electric signal, using the equipment shown in FIG. 1, was 1.70, so that a recorded pattern of high contrast, of density difference 1.57, was obtained. Moreover, no corrosion and no electrolytic-corrosion occurred in the recording medium after it was subjected to an atmosphere of 90 percent relative humidity at normal temperature.

EXAMPLE 10 In this example, the carbon black was changed to Furnace Black Seast 3H (Tokai Electrode Manuf.) which was used in an amount of 3.5 percent of a bonding agent, a mixture of phenolic modified alkyd resin. Barium sulfate powder was used for adjusting the roughness and was coated on the colored layer. A vapor-deposited aluminum layer was formed on the mixture.

A recording medium of a glossiness of 12 percent was obtained and no corrosion occurred in it at a relative humidity of 90 percent and at normal temperature.

As shown in FIG. 9, a sheet 91 was coated with conductive pigment 92 which was covered with an insulating film 93 and a vapor-deposited aluminum layer 94 was formed on the insulating film 93. Approximately the same effect as in the above examples was obtained.

EXAMPLE 11 The same recording medium as in Example 10 was made, except using MAIOO (Manuf. by Mitsubishi Kasei Industrial Co., Ltd.) for carbon black. The same results as in the Example 10 was obtained.

EXAMPLE 12 As shown in FIGS. 10A 10C, a colored layer 102 of conductive pigment with a comparatively small grain size was formed on a sheet 101. An insulating layer 103 of polyethylene was formed on colored layer 102. The surface of the insulating layer 103 in that condition was less rough and so more rough surface 104, as shown in FIG. 10C, was formed by sandblasting of abrasive with a grain size of mean diameter 0.034 to 0.02 mm. Then a vapor-deposited aluminum layer was formed on the surface 104 as shown in FIG. 10C.

The surface of the vapor-deposited aluminum layer 105 was rough and a glossiness of 15 percent was obtained. As the insulating layer 103 isolated electrically the conductive pigment 102 from the vapor-deposited aluminum layer 105, no electrolytic corrosion occurred.

EXAMPLE 13 As shown in FIG. 11, a colored layer of conductive pigment 113 was formed on a sheet of white paper of good quality with a rough surface 112 containing much clay. A vapor-deposited aluminum layer was formed on layer 113 over an insulating layer 114. The surface of the aluminum layer had a glossiness of 12.5 percent and a density of 0.16 and was not corroded at a 90 percent relative humidity and at normal temperature.

EXAMPLE 14 A colored layer containing carbon black was formed on a base paper; cellulose lacquer with dispersed silica aerogel was thinly coated on the colored layer; and then a vapor-deposited aluminum layer was formed on the cellulose lacquer. A white and less glossy vapordeposited surface having a glossiness of l 1.0 and a density of 0.07 was obtained. It was not corroded even under high humidity.

The fineness of the silica aerogel of 0.05 to 0.3 a grain size forms a most finely roughened surface. As the silica aerogel is transparent so as not to shield the black base, a recorded pattern of high contrast is obtained.

Fingerprints are often left on the surface with such a fine unevenness. To avoid leaving fingerprints, transparent powder such as glass powder with greater grain size may be mixed into the cellulose lacquer layer to form a finely uneven surface of this layer overlapped on a greatly uneven surface of the colored layer, and thus better results are obtained.

EXAMPLE 15 Black conductive pigment was coated on a paper as evenly as possible. Transparent lacquer was coated on the black conductive pigment layer in a suitable thickness. An embossing-roll or a roll roughened by sandblasting with a grain size of 0028mm was rolled on the transparent lacquer surface to form a surface dotted at an irregular pitch or an uneven surface, and aluminum was vapor-deposited thereon. Nearly the same effects as in the above examples were obtained in this example.

In Examples 8 to 15, carbon black, acetylene black and the like are used for the conductive pigment. Paintings containing conductive inorganic pigments such as minium, rouge, chromic oxide and the like with 0.02 4 0.6 [1. grain size may also be applied.

Although preferred embodiments of this invention have been described in detail with reference to the accompanying drawings, it is to be understood that the invention is not limited to the details shown and described, and that various changes and modifications can be made.

What is claimed is:

l. A recording medium for a spark burning recorder, comprising: a base having at least one organic layer containing no conductive materials thereon; a metal layer of aluminum or aluminum alloy, formed by vapor deposition, having a rough surface with a glossiness of less than twenty percent, said metal layer being in contact with said organic layer on said base containing no conductive material.

2. A recording medium for a spark burning recorder according to claim 1, wherein the base is pigmented or dyed.

3. A recording medium for a spark burning recorder according to claim 1, wherein the base comprises a pigmented or dyed layer in addition to said organic layer in contact with the metal layer and containing no conductive material.

4. A recording medium for a spark burning recorder according to claim 1, wherein the base comprises a paper, a layer containing pigment formed on the paper and an organic layer in contact with the metal layer and containing no conductive material.

5. A recording medium for a spark burning recorder according to claim 1, wherein the base comprises a first organic layer, and a second pigmented or dyed organic layer containing no conductive material in contact with the metal layer.

6. A recording medium for a spark burning recorder comprising: a base; an organic insulator layer containing no conductive material formed on said base; and a metal layer of aluminum or aluminum alloy formed on said insulator layer by vapor deposition, the glossiness of said metal layer being less than twenty percent 7. A recording medium for a spark burning recorder according to claim 6, wherein the base is pigmented or dyed and the insulating layer is not opaque.

8. A recording medium for a spark burning recorder according to claim 6, wherein the base includes a pigmented or dyed layer.

9. A recording medium for a spark burning recorder according to claim 8, wherein the pigmented or dyed layer includes conductive pigment.

10. A recording medium for a spark burning recorder according to claim 9, wherein the insulating layer comprises a transparent layer and an organic layer formed on the transparent layer and containing nonconductive particles.

11. A recording medium for a spark burning recorder according to claim 8, wherein the base includes a layer containing dye.

12. A recording medium for a spark burning recorder according to claim 11, wherein the insulator layer contains non-conductive particles. 

1. A recording medium for a spark burning recorder, comprising: a base having at least one organic layer containing no conductive materials thereon; a metal layer of aluminum or aluminum alloy, formed by vapor deposition, having a rough surface with a glossiness of less than twenty percent, said metal layer being in contact with said organic layer on said base containing no conductive material.
 2. A recording medium for a spark burning recorder according to claim 1, wherein the base is pigmented or dyed.
 3. A recording medium for a spark burning recorder according to claim 1, wherein the base comprises a pigmented or dyed layer in addition to said organic layer in contact with the metal layer and containing no conductive material.
 4. A recording medium for a spark burning recorder according to claim 1, wherein the base comprises a paper, a layer containing pigment formed on the paper and an organic layer in contact with the metal layer and containing no conductive material.
 5. A RECORDING MEDIUM FOR A SPARK BURNING RECORDER ACCORDING TO CLAIM 1, WHEREIN THE BASE COMPRISES A FIRST ORGANIC LAYER, AND A SECOND PIGMENTED OR DYED ORGANIC LAYER CONTAINING NO CONDUCTIVE MATERIAL IN CONTACT WITH THE METAL LAYER.
 6. A recording medium for a spark burning recorder comprising: a base; an organic insulator layer containing no conductive material formed on said base; and a metal layer of aluminum or aluminum alloy formed on said insulator layer by vapor deposition, the glossiness of said metal layer being less than twenty percent.
 7. A recording medium for a spark burning recorder according to claim 6, wherein the base is pigmented or dyed and the insulating layer is not opaque.
 8. A recording medium for a spark burning recorder according to claim 6, wherein the base includes a pigmented or dyed layer.
 9. A recording medium for a spark burning recorder according to claim 8, wherein the pigmented or dyed layer includes conductive pigment.
 10. A recording medium for a spark burning recorder according to claim 9, wherein the insulating layer comprises a transparent layer and an organic layer formed on the transparent layer and containing non-conductive particles.
 11. A recording medium for a spark burning recorder according to claim 8, wherein the base includes a layer containing dye.
 12. A recording medium for a spark burning recorder according to claim 11, wherein the insulator layer contains non-conductive particles. 